The Effect of Freezing in vitro on Some Transplantable Mammalian Tumors and on Normal Rat Skin

Isolated observations of the effect of freezing on various animal cells are encountered in the literature. Bacteria resist freezing to a remarkable degree, though Haines has shown that freezing of bacteria in aqueous suspension results in the death of approximately 80 per cent of the living organisms (1). Swift has been able to demonstrate that bacteria may be desiccated in the frozen state, after which their cultural, biochemical, and immunological characteristics are unaltered (2). Unicellular microorganisms resist cold in different degree. Turner noted that the treponemata of yaws and syphilis retain their normal motility and virulence for rabbits after exposure to −78° C. for four months (3). Trypanasoma gambiense withstood freezing in liquid air for twenty minutes, but not for forty minutes (4). Vegetative forms of amoebae were killed by exposure to −5° C. for five minutes in vitro (5), while malarial schizonts survived for a longer period at the same temperature (6). Encysted Trichinella spiralis failed to produce infection after exposure to −33.9° C. and viability was reduced at −27.6° C. (7).